Liquid Crystal Displays (LCDs) contain several layers which work in combination to create a viewable image. A backlight is used to generate the rays of light that pass through what is commonly referred to as the LCD stack, which typically contains several layers that perform either basic or enhanced functions. The most fundamental layer within the LCD stack is the liquid crystal material, which may be actively configured in response to an applied voltage in order to pass or block a certain amount of light which is originating from the backlight.
The light passing through each subpixel originates as “white” (or broadband) light from the backlight, although in general this light is far from being uniform across the visible spectrum. Subpixel color filters allow each subpixel to transmit a certain amount of each of several colors (e.g., red, green, blue, etc). When viewed from a distance, the subpixels appear as one composite pixel and by electrically controlling the amount of light that passes for each subpixel color, the composite pixel can produce a very wide range of different colors due to the effective mixing of light from the colored subpixels.
LCDs are becoming popular for not only home entertainment purposes, but are now being used as informational/advertising displays in both indoor and outdoor locations. When used for information/advertising purposes, the displays may remain ‘on’ for extended periods of time and thus would see much more use than a traditional home use. Further, when displays are used in areas where the ambient light level is fairly high (especially outdoors) the displays must be very bright in order to maintain adequate picture brightness. When used for extended periods of time and/or outdoors, overall energy consumption can become an issue. Thus, it is desirable to limit the power consumption of these displays as much as possible while maintaining image fidelity.
Further, arrays of LCD displays are now being used to provide very large video displays. Dynamic dimming backlights are sometimes used with these LCD displays, but this presents a number of issues when images are blended across the array of LCD displays having dynamic dimming backlights.